This invention relates to steering mechanisms and steering lines for catheter-mounted ultrasonic transducers.
Catheter-mounted ultrasonic transducers are known to the art, as described for example in U.S. Pat. No. 4,794,931 and 5,368,037. These catheter-mounted transducers are single use, disposable devices which provide a radial image format either by means of a radial phased array or a rotating crystal. These devices do not include any mechanism for steering or articulating the tip of the catheter. Because the catheter tip cannot be steered, it is in general not possible to position the transducer optimally to obtain different views of the tissue or structure being imaged.
Catheters other than ultrasonic imaging catheters currently exist which have articulating tips. One typical steering mechanism for such a catheter uses a knob which rotates about an axis perpendicular to the length of the catheter. As the user rotates the knob clockwise or counterclockwise, the tip of the catheter will articulate either up and down, or left and right. In addition to manipulating the catheter tip with the knob, the catheter is generally rotated within the vessel by rotating the control housing. Such rotation of the control housing causes the knob to rotate as well as the catheter, and can place the knob in an relatively inaccessible position for the user. Awkward positioning of the steering knob can make manipulating the catheter tip difficult.
Accisano U.S. Pat. No. 5,571,085 and Fleischhackor U.S. Pat. No. 5,395,329 disclose control handles for steerable catheters which utilize a rotating collar to move a slide longitudinally in the catheter handle. Steering lines are connected to the slide such that reciprocation of the slide steers the distal tip of the catheter. This arrangement provides the advantage of a steering actuator which extends around the complete circumference of the handle and rotates about the longitudinal axis of the handle.